Re: A brief commentary

From: (Alan Browne)
Organization: Canadian Marconi Company
Date:         04 Aug 96 16:44:59 
References:   1 2
Followups:    1
Next article
View raw article
  or MIME structure

I'll just throw in some bull for good measure...

In the string of articles above, there is mention of spatial disorientation.
All pilots, as has been mentioned, have experienced various degrees of
vertigo and disorientation.  It is a unique sensation, and usually fairly
easy to override when it is identified.  But throw in a bunch of other
"distractors" and the vertigo or disorientation can overpower.

A B-737 in Latin America took off one night and sometime after reaching
cruise suddenly rolled off and then spiraled into the jungle.

It was later determined that the VG channel had failed.  Also both the
captain and FO were tied to the same VG, because one of the VG's was TU.

So as the reference VG failed and the ADI roled over, the pilot counter
rolled to remain level. no avail, so roll even harder...  soon they
were in a spiral and never recovered.

What I fail to understand is why they did not check the standby attitude
indicator.  The crew presumably knew that since they were both tied to the
same VG, that any cross checking should be with the standby indicator.

Also, basic instrument flying dictates that a banked attitude will produce a
turn...if they had checked the HSI, they would have seen whether or not they
were turning...if they ain't changing heading then there is something wrong
with this bank attitude indication.

It is my belief that generally airline cockpit instruments are SO reliable
that pilots get lured into always believing what they see.  This makes
identifying a failed instrument late...and puts the aircraft in a position
that is increasingly difficult to recover from...

The above is just my opinion.
Alan Browne